I just purchased a 2008 5500 with the 6.7 and has Jake brake. Only 41000 miles from a township. Did a lot of idling. I noticed that it acts when I first start that either the Jake is on with the switched disengaged or its trying to regenerate.
After a few seconds 30-60 it then runs normal. But while driving it has a regular pattern of loss of power and a Jake brake sound for under 5 seconds. What could the issue be